Tuesday, March 25, 2008

At conception, you become a fetus, with your very own set of genes. Your town meeting is populated and you’re ready to spend the next nine months in the womb, interacting with your prenatal environment–amniotic fluid, placenta, and a host of other influences. You’ll also respond to your prenatal “diet”–the nutrition you take in through what your mother eats and makes available to you. So right from the beginning, your town meeting is under way, with diet, environment, and genes beginning their lively debate.

This debate has enormous significance for the being who will emerge into the world nine months later. For example, your genetic potential at conception encoded a certain range of arterial flexibility. But how strong will your arteries be, and how flexible? A lot of the answers to those questions depend on what happens in the womb.

So that’s one of your first town meetings. The genes that encode the delicate branching architecture of your nerves and arteries show up, ready to take part. And there are our friends, environment and diet, up there on the platform as they will be throughout your life, helping your “cardiovascular genes” and “nerve genes” decide what to do. A good diet with lots of protein and healthy fats will encourage your artery genes to make your arteries rugged and elastic. On the other hand, if your mother is unlucky enough to be living in a famine, your “artery genes” will have to compete for those scarce nutrients with the genes that control the growth of other organs andtissues. The result might be a greater tendency for heart disease or high blood pressure. As you can see, the same genes are always at the meeting, but they’re responding very differently to the information given by diet and environment.

Obviously, the health of your arteries is only one of the ways that your tissues and organs are affected by your time in the womb. Those crucial nine months help determine whether you gain weight at the drop of a hat or lose weight far too easily. They help nudge you toward a hair-trigger immune response that views the entire world as its enemy, or toward a welcoming immune response that may not always know which invaders to turn away. They predispose you to certain foods that you’ll be able to digest easily and turn you away from others that won’t suit your particular metabolism and digestive tract. Right from the beginning, your genes interact with diet (in this case, Mom’s) and environment (in this case, the womb) to determine who you are.

And then you’re born. This is the point at which your GenoType is determined. Your GenoType represents your survival strategy, the decisions that have been reached collectively among your genetic potential, your prenatal diet, and your environment. Although the town meeting will continue for the rest of your life, with genes getting louder and softer in response to diet and environment, certain elements of this meeting are now fixed. They’ve formed certain patterns–one of six patterns, to be exact, which I’ve identified as the six human GenoTypes.

GenoTypes: A Human Survival Strategy

So far, we’ve been telling the story from an individual point of view–yours, to be exact. But since everyone in the world falls into one of those six GenoTypes, let’s step back for a moment and see where these GenoTypes came from.

In the beginning was the environment–a challenging place for our ancestors, to be sure. People had to make sure they could get enough food, that they could survive whatever climate they were born in or migrated to, and that they could resist infections from microbes, bacteria, and viruses.

Genetic inheritance played a crucial role in this survival. People with helpful genes survived; people with less helpful genes died. You’ve probably heard of this particular aspect of evolution as “survival of the fittest.”

Actually, survival of the fittest is more a fantasy than a reality. If only we humans were the fittest possible examples of our species, we’d all be a lot healthier, and I might be out of a job! In fact, evolution is more like a game of chance than any true contest. Sometimes the good players win; sometimes it’s just the lucky ones who survive. Sure, a lot of our genetic inheritance helps us beat the odds, but there’s also a big chunk of it that gets in our way or doesn’t play any useful role at all:

1. Sometimes the “good genes” that help us survive also have their downside. The genes that instruct our immune systems to react swiftly to bacterial invasion also overreact to produce allergies, asthma, and rheumatoid arthritis. The genes that instruct our fat cells to hang on to every calorie in order to survive a famine also contribute to obesity and diabetes. The genes that program our immune systems to respond calmly to the environment, enabling us to tolerate a wide set of circumstances without getting sick, also tell that immune system to tolerate some deadly invaders that it ought to repel.

2. Sometimes mutations simply “happen.” Our genes are designed to reproduce themselves in exact copies, but of course, that’s not always how it works. Sometimes a gene reproduces slightly differently and that variation becomes part of our genetic heritage. Skin color probably emerged this way, as a mutation of the gene that determines skin pigment. Although originally we all had dark skin, those of us living in northern climates were better able to absorb vitamin D from the scarce sunlight if our skin was lighter; we also had less need of the darker pigment’s protective function. So having lighter skin was a mutation that survived because it actually did contribute to our survival.

To some extent, though, these mutations were just random, such as the mutations that produced such diseases as Huntington’s chorea or Tay-Sachs. Or, sometimes, they represent a trade-off between the lesser of two evils. For example, having sickle-cell anemia seems to be somewhat protective against malaria, so people with the genetic tendency to have one disease are meanwhile being protected against another.

As you can see, some mutations make our lives better, some make them worse, and some probably don’t make much difference either way. But the “bad” or “neutral”mutations don’t necessarily die out, and as we’ll see in a moment, the good ones don’t necessarily survive.

3. Sometimes who survives is just the luck of the draw. If all the strong young men die in a huge battle, the male survivors are not necessarily the healthiest–but they will have lived the longest. If an avalanche destroys three-fourths of a village, the remaining one-fourth who stagger down the mountain may be more lucky than fit. There is also what scientists call the “founder effect”: When a small group splits off from a larger group and migrates to a distant land, its members may carry only a fraction of the original population’s genetic potential. Whatever genes they managed to take away from the larger group, those are the ones that survive–and they’re not necessarily “the fittest.” Nevertheless, these are the survivors, the ones who pass their genetic inheritance down to the rest of us.

Why should you care about any of this? Because the final effect of this whole process has been our six GenoTypes, which are extremely useful but very imperfect strategies for survival. Every GenoType has its upside and its downside. I personally can imagine ways to improve every single one of them, and once you get to know them better, I’m sure you will, too. In fact, that’s the point of this book: What the GenoTypes have begun, we can complete, maximizing their strengths and minimizing their weaknesses through diet, supplements, and exercise.

Remember, your genes don’t stay fixed in their tracks. Instead, they keep reshaping themselves and you, just as they did when you were in the womb. Your cells are constantly reading the environment they’re in and altering their functions accordingly: Toxic or safe? Food-rich or barren? Threatening or welcoming? These conditions prompt your cells to turn various genes on and off, depending on how the environment is affecting them. These instructions are implemented at the town meeting, where the volume is turned up on some genes and turned down on others.

The end result is our six GenoTypes, each of which has its own unique pattern of “noisy” and “silent” genes. Accordingly, each of our six GenoType Diets is designed to alter that pattern to promote your optimal health and weight.Meet the GenoTypesSo let’s take a closer look at these GenoTypes. What possibilities for human survival are encoded within these genetic and prenatal patterns? Before I introduce you to the GenoTypes, I want to caution you against two common mistakes. First, these GenoTypes do not correlate in any way to ethnic patterns. They seem to have developed tens of thousands of years before ethnicity emerged, and with the exception of the Nomad GenoType, which seems to have more than its fair share of redheads, they don’t follow any of the statistical patterns that do correlate with ethnicity, skin color, eye color, hair texture, hair color, ancestry information markers, mitochondrial DNA, Y-chromosome DNA, and a host of others with far more technical names. In the end, I could find only afew weak links with some of the ancestral DNA markers but absolutely no correlation with ethnicity–none. Just as anyone can be hot-tempered or optimistic, anyone can be any one of these GenoTypes, no matter their racial or ethnic identity or who their ancestors are. (And, just to make this crystal clear, no one can use this theory to “prove” that any ethnic group is superior to any other!)

Second, although I think it’s useful to speculate on how these GenoTypes emerged, I don’t really have the archaeological or anthropological evidence to tell that story. I know that six GenoTypes exist now, and I can deduce how they developed, but that’s the part of the story for which the evidence is still largely circumstantial. That’s because I’ve worked backward–I’ve identified the six GenoTypes that currently exist and then speculated about how they got here. Someone else will have to fill in the rest. Meanwhile, all you need to know is that by following the correct diet for your GenoType, you can multiply exponentially your chances for health, vitality, and maintaining your ideal weight.

So let’s meet the GenoTypes! You’ll read about each of them in depth in Part III, but here’s a preview that makes it clear how each GenoType represents a unique survival strategy. I like to think of them as easily recognizable archetypes, striding over the challenging terrain of the Paleolithic and Neolithic planet. Each GenoType has unique strengths that give them an advantage when dealing with food shortages, climate change, and infectious diseases, and each of them has unique weaknesses as well.GenoType 1: The Hunter. This is one of the earliest surviving responses to the challenge of human survival. Beleaguered by what must have seemed like an overwhelming set of environmental challenges–hunger, climate, infectious diseases–Hunters exemplify a reactive approach, a quick and powerful response to every potential threat. “Shoot first and ask questions later” might be their motto. The upside: They’ve got immune systems that act swiftly to attack microbes, viruses, and bacteria that try to kill them, and they’re terrific at metabolizing the meat that is their primary source of nutrition. The downside: Their hair-trigger immune response can sometimes lead to overreaction in the form of allergies, asthma attacks, and other inflammatory conditions. Sometimes, as with the viral gastroenteritis to which they’re also prone, their immune response may target their own tissue as part of its effort to repel the invaders, a kind of “friendly fire” that can create more health problems than it solves. Another downside is Hunters’ inability to digest grains and some other types of food–it’s just not what their system is geared for. So our GenoType 1 Diet for Hunters helps calm their immune systems and keeps them away from the kinds of “reactive proteins”–lectins and glutens–that are likely to set them off.

GenoType 2: The Gatherer. If you need to survive a famine–and many of our ancestors did–GenoType 2 is designed to get you through it. Gatherers have thrifty genes whose primary goal is to hang on to every ingested calorie for dear life–literally. If the Hunter’s motto is “Shoot first and ask questions later,” the Gatherer lives by “Whoever dies with the most wins.” Gatherers learned in the womb that there wouldn’t be much food when they got out, so their town meeting quickly worked out a system whereby food conservation was its top priority. The upside to this approach is obvious: It kept them alive and able to bear or father children. The downside is equally obvious: In a more affluent society, Gatherers tend toward obesity and diabetes. Many of my Gatherer patients assure me that they’ve cut down their caloric intake to an almost starvation level–and yet they still can’t lose weight. No wonder: The more they starve themselves, the more their town meetings insist on hoarding food! Our GenoType 2 Diet helps Gatherers rev up that sluggish metabolism and return to their ideal weight, reducing the risk of diabetes and reversing the negative consequences of obesity.

GenoType 3: The Teacher. The Teacher represents the third basic response to a challenging world: altruism. “All you need is love” is the Teachers’ motto, and their immune systems reflect it. Perhaps because this GenoType emerged during a time when people were migrating more and living in more varied environments, Teachers are able to tolerate a wide variety of unfamiliar bacteria, viruses, and microbes, avoiding the hairtrigger symptoms that plague the Hunter. Unfortunately, they sometimes welcome infectious elements that they would do better to repel. Teachers may live for a long time without symptoms and then discover that digestive problems, lung disorders, or even cancer have been building within them for years. Our goal for Teachers is to protect their stomachs, colons, and lungs from the wear and tear of the environment .We want to keep their “good bacteria” happy and numerous so they can crowd out the disease-causing “bad” bacteria, yeast, and viruses. We also want to make their immune defenses more efficient by “teaching” them with food, supplements, and lifestyle to be more protective and discriminating.

GenoType 4: The Explorer. The first three GenoTypes were probably developed by our ancestors some 50,000 to 75,000 years ago. The Explorer is a newer model, maybe about 20,000 to 30,000 years old. Like Hunters, they’re reactive, but unlike Hunters, they’re highly idiosyncratic, reacting intensely to some environmental threats and not at all to others. For example, if you’re one of those folks who can’t drink coffee because it keeps you up all night, you’re almost certainly an Explorer. I have no idea whether Frank Sinatra was an Explorer, but he did popularize their motto, which is “I did it my way.” My theory is that in every population, you need some folks who do things very differently, so that if the majority turns out to be wrong, someone is there to offer an alternative. Explorers can do that–but sometimes they just seem naturally contrary. They’re more often left-handed, Rh-negative, and asymmetrical: Their left and right sides don’t match, right down to their fingerprints. They seem to have their own ways of digesting food, responding to disease, and otherwise coping with an ever-changing, unpredictable environment. I think of them as glacial refugees, continually forced from one home to another as they tried to escape the ice. They never had the chance to settle down into a stable relationship with one environment, so they couldn’t afford the blanket reactivity of the Hunter. Accordingly, they fine-tuned their responses–but in unpredictable and sometimes inexplicable ways. In modern times, they seem to have emerged from a highly unstable prenatal environment (asymmetry is usually a sign of that), and they’ve figured out while still in the womb that they’re going to have to adapt to wildly changing conditions. Their upside is that they’re good at that. Their downside is that odd things–like caffeine–can keep them up for hours. Our dietary goal for them is to develop calmer, more stable responses to the world, protecting them from their idiosyncratic but very vulnerable Achilles’ heels.

GenoType 5: The Warrior. Like the Gatherer, Warriors are a Thrifty GenoType, but I believe they, too, are a newer GenoType, perhaps dating from the Neolithic Revolution (about 11,000 B.C.E.) to the Iron Age (starting around 2000 B.C.E.). Instead of displaying the overwhelming thriftiness of the Gatherers, who hoard pretty much any calorie they can get their hands on, Warriors are more selective. If they’re physically active, their metabolism burns hot; when they lead a sedentary life, they tend to put on the pounds with alarming speed. I’ve called them “Warriors,” but perhaps “war survivors” would have been a better name: I’ve often thought that this GenoType developed in response to the scarcity of the post-Neolithic period, when agricultural technology was still at a very low level, trade was limited, and there were enormous disruptions resulting from war and the spread of “civilization.” Earlier in our history, most disasters were natural; then we started creating human-made catastrophes–war, conquest–and I think the Warriors were among the first survivors of these. The survivors in these warrior societies often had to produce large numbers of children, who had an urgent need to progress rapidly to adulthood. In a sense, their genetic inheritance is like the multiple copies of the photocopy machine, getting blurrier and less reliable with each replication. On the other hand, the harsh conditions of this “survivor” life have given Warriors some remarkable strengths: endurance, stamina. “Time flies when you’re having fun” might be their motto–but luckily, with the GenoType Diet, we can do a lot to prolong their life, health, and vitality. (I have a vested interest in the matter, since I’m a Warrior myself!)

GenoType 6: The Nomad. The Nomad is also a newer GenoType. Their survival strategy reflects a life of travel, encountering different environments and having to cope with a wide variety of challenges. Some of the first people to create a migratory life based upon the use of the horse, Nomads moved quickly over large swaths of territory, passing through a wide variety of climates and terrains. In such a life, any single survival strategy would have only a limited value, and it wouldn’t pay to be too reactive to any particular environmental factor. You’d have to learn tolerance–but a limited tolerance, taking in only so much of your environment and keeping your guard up at least some of the time. “A new career in a new town” is the Nomads’ motto, and, like the Teachers, their response to the environment is more toward the altruistic, tolerant side. They’re a bit more selective than Teachers, though, and somewhat better at filtering out hostile invaders like microbes and bacteria. The price they pay for their more selective immunity is a problematic connection between their immune system, their cardiovascular system, and their nervous system, resulting in a lack of coordination among the three. This makes the Nomad prone to highly idiosyncratic health problems, such as chronic viral infections, debilitating long-term fatigue, and memory problems. Although these are physical problems for sure, they are also often the result of a much deeper disconnect between the Nomad’s mind and body. Although well-functioning Nomads usually have wonderful abilities to heal their bodies through visualization, meditation, and relaxation, stress can cause their normal mind-body integration to disconnect so that their physical systems spin out of control. Our goal here is to defend those few places where Nomads’ immune systems are susceptible to problems and to increase communication within their bodies.

Now you’ve got some idea of how the GenoTypes developed and a thumbnail sketch of each GenoType.You may be wondering how you can determine which GenoType you are.You can just take my word for it, figure out your GenoType in Part II, discover your GenoType in Part III, and begin following the diet for your GenoType in Part IV. But if you’d like to know more about what those tests are based on, turn the page and start reading Chapter 2.

Excerpted fromThe GenoType Diet: Change Your Genetic Destiny to live the longest, fullest and healthiest life possibleby Peter J. D'AdamoBuy this book at Barnes & Noble